This invention relates to the cooling of hot dry air by indirect or direct means, or a combination thereof, employing a compact apparatus which efficiently utilizes the capacity of dry air to evaporate water.
Evaporative coolers have been employed for many years to cool air in homes, farm buildings, commercial buildings, industrial buildings and to provide spot cooling. For example, spot evaporative coolers are sold commercially to cool air in workshops, garages, greenhouses, etc. The technology and apparatuses now available are described in Chapter 19 of ASHRAE's 1996 HVAC Systems and Equipment book and in Chapter 47 of ASHRAE's 1995 HVAC Applications book. A study of these references discloses that indirect cooling devices always are separated from direct cooling devices and these devices may be interconnected by air ducting to achieve desired synergistic cooling effects.
The process of evaporative cooling exchanges the latent heat of water for the sensible heat of air and, consequently, is environmentally benign. The mechanical energy that must be provided for this exchange is a small fraction of the energy required in the more conventional vapor compression devices for an equivalent amount of cooling. Evaporative cooling, however, is only effective as a stand-alone device in approximately one-half the land area of the world, wherein the dry bulb temperatures are 95.degree. F. or higher and the concomitant wet bulb temperatures are 70.degree. F. or lower.